Autophagy is increased in postmortem brains of persons with HIV-1-associated encephalitis

Molecular Mechanisms Associated with Neurodegeneration of Neurotropic Viral Infection

Viral infections of the central nervous system (CNS) cause variable outcomes from acute to severe neurological sequelae with increased morbidity and mortality. Viral neuroinvasion directly or indirectly induces encephalitis via dysregulation of the immune response and contributes to the alteration of neuronal function and the degeneration of neuronal cells. This review provides an overview of the cellular and molecular mechanisms of virus-induced neurodegeneration. Neurotropic viral infections influence many aspects of neuronal dysfunction, including promoting chronic inflammation, inducing cellular oxidative stress, impairing mitophagy, encountering mitochondrial dynamics, enhancing metabolic rewiring, altering neurotransmitter systems, and inducing misfolded and aggregated pathological proteins associated with neurodegenerative diseases. These pathogenetic mechanisms create a multidimensional injury of the brain that leads to specific neuronal and brain dysfunction. The understanding of the molecular mechanisms underlying the neurophathogenesis associated with neurodegeneration of viral infection may emphasize the strategies for prevention, protection, and treatment of virus infection of the CNS.

Molecular Role of HIV-1 Human Receptors (CCL5-CCR5 Axis) in neuroAIDS: A Systematic Review

Chronic HIV-1 infection can cause neurological illness, also known as HIV-associated neurocognitive disorders (HAND). The elevated level of pro-inflammatory cytokines and chemokines, such as C-C Chemokine Ligand 5 (CCL5/RANTES), is one of the ways of causing HIV-1-mediated neuroinflammation. C-C Chemokine Receptor 5 (CCR5) is the main coreceptor for viral entry into host cells and for mediating induction of CCL5/RANTES. CCR5 and CCL5 are part of a correlated axis of immune pathways used for effective protection against the HIV-1 virus. The purpose of this paper was to review the literary knowledge about the immunopathological relationship between this immune complex and neuroAIDS. A systematic review of the literature was conducted based on the selection and search of articles, available in English, Spanish, or Portuguese in the time frame of 1990-2022, of primary and secondary types in the PUBMED, Science Direct, SciELO, and LILACS databases through descriptors (MeSH) together with "AND": "CCR5"; "CCL5"; "neurological manifestations"; or "HIV". The methodological quality of the articles was assessed using the JBI Checklists and the PRISMA 2020 writing guidelines were followed. A total of 36 articles were included in the final composition of the review. The main cells of the CNS affected by neuroAIDS are: neurons; microglia; astrocytes; and oligodendrocytes. Molecular devices and their associations with cellular injuries have been described from the entry of the virus into the host's CNS cell to the generation of mental disorders. Furthermore, divergent results were found about the levels of CCL5/RANTES secretion and the generation of immunopathogenesis, while all condensed research for CCR5 indicated that elevation of this receptor causes more neurodegenerative manifestations. Therefore, new therapeutic and interventional strategies can be conditioned on the immunological direction proposed in this review for the disease.

Exosome-Autophagy Crosstalk in Enveloped Virus Infection

Exosomes, which are extracellular vesicles (EVs) predominantly present in bodily fluids, participate in various physiological processes. Autophagy, an intracellular degradation mechanism, eliminates proteins and damaged organelles by forming double-membrane autophagosomes. These autophagosomes subsequently merge with lysosomes for target degradation. The interaction between autophagy and endosomal/exosomal pathways can occur at different stages, exerting significant influences on normal physiology and human diseases. The interplay between exosomes and the autophagy pathway is intricate. Exosomes exhibit a cytoprotective role by inducing intracellular autophagy, while autophagy modulates the biogenesis and degradation of exosomes. Research indicates that exosomes and autophagy contribute to the infection process of numerous enveloped viruses. Enveloped viruses, comprising viral nucleic acid, proteins, or virions, can be encapsulated within exosomes and transferred between cells via exosomal transport. Consequently, exosomes play a crucial role in the infection of certain viral diseases. This review presents recent findings on the interplay between exosomes and autophagy, as well as their implications in the infection of enveloped viruses, thereby offering valuable insights into the pathogenesis and vaccine research of enveloped virus infection.

Different Roles of Beclin1 in the Interaction Between Glia and Neurons after Exposure to Morphine and the HIV- Trans-Activator of Transcription (Tat) Protein

Previously we showed that Beclin1 has a regulatory role in the secretion of inflammatory molecules in glia after exposure to morphine and Tat (an HIV protein). Here we show increased secretion of neuronal growth factors and increased neuronal survival in Beclin1-deficient glia. However, without glia co-culture, neurons deficient in Beclin1 showed greater death and enhanced dendritic beading when compared to wild-type neurons, suggesting that glial-secreted growth factors compensate for the damage reduced autophagy causes neurons. To assess if our ex vivo results correlated with in vivo studies, we used a wild-type (Becn1+/+) and Beclin1-deficient (Becn1+/+) mouse model and intracranially infused the mice with Tat and subcutaneously administered morphine pellets. After morphine implantation, significantly impaired locomotor activities were detected in both Becn1+/+ and Becn1+/- mice, irrespective of Tat infusion. After induction of pain, morphine-induced antinociception was detected. Interestingly, co-exposure to morphine and Tat increased sensitivity to pain in Becn1+/+ mice, but not in similarly treated Becn1+/- mice. Brain homogenates from Becn1+/+ mice exposed to Tat, alone and in combination with morphine, showed increased secretion of pro-inflammatory cytokines and reduced expression of growth factors when compared to similarly treated Becn1+/- mice. Likewise, increased neuronal loss was detected when both Tat and morphine were administered to Becn1+/+ mice, but not in similarly treated Becn1+/- mice. Overall, our findings show that there is a Beclin1-driven interaction between Tat and morphine in glia and neurons. Moreover, reduced glial-Beclin1 may provide a layer of protection to neurons under stressful conditions, such as when exposed to morphine and Tat.

Clearance of HIV-1 or SIV reservoirs by promotion of apoptosis and inhibition of autophagy: Targeting intracellular molecules in cure-directed strategies

The reservoirs of the HIV display cellular properties resembling long-lived immune memory cells that could be exploited for viral clearance. Our interest in developing a cure for HIV stems from the studies of immunologic memory against infections. We and others have found that long-lived immune memory cells employ prosurvival autophagy and antiapoptotic mechanisms to protect their longevity. Here, we describe the rationale for the development of an approach to clear HIV-1 by selective elimination of host cells harboring replication-competent HIV (SECH). While reactivation of HIV-1 in the host cells with latency reversing agents (LRAs) induces viral gene expression leading to cell death, LRAs also simultaneously up-regulate prosurvival antiapoptotic molecules and autophagy. Mechanistically, transcription factors that promote HIV-1 LTR-directed gene expression, such as NF-κB, AP-1, and Hif-1α, can also enhance the expression of cellular genes essential for cell survival and metabolic regulation, including Bcl-xL, Mcl-1, and autophagy genes. In the SECH approach, we inhibit the prosurvival antiapoptotic molecules and autophagy induced by LRAs, thereby allowing maximum killing of host cells by the induced HIV-1 proteins. SECH treatments cleared HIV-1 infections in humanized mice in vivo and in HIV-1 patient PBMCs ex vivo. SECH also cleared infections by the SIV in rhesus macaque PBMCs ex vivo. Research efforts are underway to improve the efficacy and safety of SECH and to facilitate the development of SECH as a therapeutic approach for treating people with HIV.

Methamphetamine Dysregulates Macrophage Functions and Autophagy to Mediate HIV Neuropathogenesis

HIV-neurocognitive impairment (HIV-NCI) can be a debilitating condition for people with HIV (PWH), despite the success of antiretroviral therapy (ART). Substance use disorder is often a comorbidity with HIV infection. The use of methamphetamine (meth) increases systemic inflammation and CNS damage in PWH. Meth may also increase neuropathogenesis through the functional dysregulation of cells that harbor HIV. Perivascular macrophages are long-lived reservoirs for HIV in the CNS. The impaired clearance of extracellular debris and increased release of reactive oxygen species (ROS) by HIV-infected macrophages cause neurotoxicity. Macroautophagy is a vital intracellular pathway that can regulate, in part, these deleterious processes. We found in HIV-infected primary human macrophages that meth inhibits phagocytosis of aggregated amyloid-β, increases total ROS, and dysregulates autophagic processes. Treatment with widely prescribed ART drugs had minimal effects, although there may be an improvement in phagocytosis when co-administered with meth. Pharmacologically inhibited lysosomal degradation, but not induction of autophagy, further increased ROS in response to meth. Using mass spectrometry, we identified the differentially expressed proteins in meth-treated, HIV-infected macrophages that participate in phagocytosis, mitochondrial function, redox metabolism, and autophagy. Significantly altered proteins may be novel targets for interventional strategies that restore functional homeostasis in HIV-infected macrophages to improve neurocognition in people with HIV-NCI using meth.

Modulation of the autophagic pathway inhibits HIV-1 infection in human lymphoid tissue cultured ex vivo

A complex link exists between HIV-1 and autophagy, and discordant results have been reported in different in vitro models regarding the way HIV and autophagy modulate each other. Despite this, there is very limited knowledge about the interplay between HIV and autophagy in vivo in lymphoid tissue, due in part by the lack of cell models that recapitulate the in vivo setting. Here, we evaluate the interrelationship between HIV and autophagy using human ex vivo lymphoid tissue cultures as an HIV infection model. Our results showed that human lymphoid aggregated cultures (HLACs) from tonsillar tissue displayed fully functional autophagic activity. In this system, HIV infection resulted in an increase in autophagy. Notably, we observed that both, autophagy-enhancing (rapamycin) or blocking drugs (3-methyladenine, chloroquine and bafilomycin), were able to decrease HIV-DNA levels and HIV replication. Therefore, efficient HIV-1 replication requires a fine-tuned level of autophagy, so modifications of this balance will have a negative impact on its replication. Therefore, targeting the autophagic pathway could be a new therapeutic approach to be explored to treat HIV-1 infection. Ex vivo cultures of human lymphoid tissue are a suitable model to obtain further insights into HIV and its intricate relationship with autophagy.

HIV-1 Tat endocytosis and retention in endolysosomes affects HIV-1 Tat-induced LTR transactivation in astrocytes

The presence of latent HIV-1 reservoirs in the periphery and brain represents a major obstacle to curing HIV-1 infection. As an essential protein for HIV-1 viral replication, HIV-1 Tat, mostly intracellular, has been implicated in latent HIV-1 infection. From HIV-1 infected cells, HIV-1 Tat is actively secreted and bystander cells uptake the released Tat whereupon it is endocytosed and internalized into endolysosomes. However, to activate the HIV-1 LTR promoter and increase HIV-1 replication, HIV-1 Tat must first escape from the endolysosomes and then enter the nucleus. Here, we tested the hypothesis that HIV-1 Tat can accumulate in endolysosomes and contribute to the activation of latent HIV-1 in astrocytes. Using U87MG astrocytoma cells expressing HIV-1 LTR-driven luciferase and primary human astrocytes we found that exogenous HIV-1 Tat enters endolysosomes, resides in endolysosomes for extended periods of time, and induces endolysosome de-acidification as well as enlargement. The weak base chloroquine promoted the release of HIV-1 Tat from endolysosomes and induced HIV-1 LTR transactivation. Similar results were observed by activating endolysosome Toll-like receptor 3 (TLR3) and TLR7/8. Conversely, pharmacological block of TLRs and knocking down expression levels of TLR3 and TLR7, but not TLR8, prevented endolysosome leakage and attenuated HIV-1 Tat-mediated HIV-1 LTR transactivation. Our findings suggest that HIV-1 Tat accumulation in endolysosomes may play an important role in controlling HIV-1 transactivation.

Reduced neuronal population in the dorsolateral prefrontal cortex in infant macaques infected with simian immunodeficiency virus (SIV)

Pediatric HIV infection remains a global health crisis with an estimated 150,000 new mother-to-child (MTCT) infections each year. Antiretroviral therapy (ART) has improved childhood survival, but only an estimated 53% of children worldwide have access to treatment. Adding to the health crisis is the neurological impact of HIV on the developing brain, in particular cognitive and executive function, which persists even when ART is available. Imaging studies suggest structural, connectivity, and functional alterations in perinatally HIV-infected youth. However, the paucity of histological data limits our ability to identify specific cortical regions that may underlie the clinical manifestations. Utilizing the pediatric simian immunodeficiency virus (SIV) infection model in infant macaques, we have previously shown that early-life SIV infection depletes the neuronal population in the hippocampus. Here, we expand on these previous studies to investigate the dorsolateral prefrontal cortex (dlPFC). A total of 11 ART-naïve infant rhesus macaques (Macaca mulatta) from previous studies were retrospectively analyzed. Infant macaques were either intravenously (IV) inoculated with highly virulent SIVmac251 at ~1 week of age and monitored for 6-10 weeks or orally challenged with SIVmac251 from week 9 of age onwards with a monitoring period of 10-23 weeks post-infection (19-34 weeks of age), and SIV-uninfected controls were euthanized at 16-17 weeks of age. Both SIV-infected groups show a significant loss of neurons along with evidence of ongoing neuronal death. Oral- and IV-infected animals showed a similar neuronal loss which was negatively correlated to chronic viremia levels as assessed by an area under the curve (AUC) analysis. The loss of dlPFC neurons may contribute to the rapid neurocognitive decline associated with pediatric HIV infection.

Important role of microglia in HIV-1 associated neurocognitive disorders and the molecular pathways implicated in its pathogenesis

The development of effective combined anti-retroviral therapy (cART) led to a significant reduction in the death rate associated with human immunodeficiency virus type 1 (HIV-1) infection. However, recent studies indicate that considerably more than 50% of all HIV-1 infected patients develop HIV-1-associated neurocognitive disorder (HAND). Microglia are the foremost cells infected by HIV-1 in the central nervous system (CNS), and so, are also likely to contribute to the neurotoxicity observed in HAND. The activation of microglia induces the release of pro-inflammatory markers and altered secretion of cytokines, chemokines, secondary messengers, and reactive oxygen species (ROS) which activate signalling pathways that initiate neuroinflammation. In turn, ROS and inflammation also play critical roles in HAND. However, more efforts are required to understand the physiology of microglia and the processes involved in their activation in order to better understand the how HIV-1-infected microglia are involved in the development of HAND. In this review, we summarize the current state of knowledge about the involvement of oxidative stress mechanisms and role of HIV-induced ROS in the development of HAND. We also examine the academic literature regarding crucial HIV-1 pathogenicity factors implicated in neurotoxicity and inflammation in order to identify molecular pathways that could serve as potential therapeutic targets for treatment of this disease. KEY MESSAGES Neuroinflammation and excitotoxicity mechanisms are crucial in the pathogenesis of HAND. CNS infiltration by HIV-1 and immune cells through the blood brain barrier is a key process involved in the pathogenicity of HAND. Factors including calcium dysregulation and autophagy are the main challenges involved in HAND.

HIV Increases the Inhibitory Impact of Morphine and Antiretrovirals on Autophagy in Primary Human Macrophages: Contributions to Neuropathogenesis

HIV enters the CNS early after peripheral infection, establishing reservoirs in perivascular macrophages that contribute to development of HIV-associated neurocognitive disorders (HAND) in 15–40% of people with HIV (PWH) despite effective antiretroviral therapy (ART). Opioid use may contribute to dysregulated macrophage functions resulting in more severe neurocognitive symptoms in PWH taking opioids. Macroautophagy helps maintain quality control in long-lived cell types, such as macrophages, and has been shown to regulate, in part, some macrophage functions in the CNS that contribute to HAND. Using Western blotting and confocal immunofluorescence in primary human macrophages, we demonstrated that morphine and a commonly prescribed ART regimen induce bulk autophagy. Morphine and ART also inhibited completion of autophagy. HIV infection increased these inhibitory effects. We also examined two types of selective autophagy that degrade aggregated proteins (aggrephagy) and dysfunctional mitochondria (mitophagy). Morphine and ART inhibited selective autophagy mediated by p62 regardless of HIV infection, and morphine inhibited mitophagic flux in HIV-infected cells demonstrating potential mitotoxicity. These results indicate that inhibition of autophagy, both in bulk and selective, in CNS macrophages may mediate neurocognitive dysfunction in PWH using opioids. Increasing autophagic activity in the context of HIV may represent a novel therapeutic strategy for reducing HAND in these individuals.

The Interplay of HIV and Autophagy in Early Infection

HIV/AIDS is still a global threat despite the notable efforts made by the scientific and health communities to understand viral infection, to design new drugs or to improve existing ones, as well as to develop advanced therapies and vaccine designs for functional cure and viral eradication. The identification and analysis of HIV-1 positive individuals that naturally control viral replication in the absence of antiretroviral treatment has provided clues about cellular processes that could interact with viral proteins and RNA and define subsequent viral replication and clinical progression. This is the case of autophagy, a degradative process that not only maintains cell homeostasis by recycling misfolded/old cellular elements to obtain nutrients, but is also relevant in the innate and adaptive immunity against viruses, such as HIV-1. Several studies suggest that early steps of HIV-1 infection, such as virus binding to CD4 or membrane fusion, allow the virus to modulate autophagy pathways preparing cells to be permissive for viral infection. Confirming this interplay, strategies based on autophagy modulation are able to inhibit early steps of HIV-1 infection. Moreover, autophagy dysregulation in late steps of the HIV-1 replication cycle may promote autophagic cell-death of CD4⁺ T cells or control of HIV-1 latency, likely contributing to disease progression and HIV persistence in infected individuals. In this scenario, understanding the molecular mechanisms underlying HIV/autophagy interplay may contribute to the development of new strategies to control HIV-1 replication. Therefore, the aim of this review is to summarize the knowledge of the interplay between autophagy and the early events of HIV-1 infection, and how autophagy modulation could impair or benefit HIV-1 infection and persistence, impacting viral pathogenesis, immune control of viral replication, and clinical progression of HIV-1 infected patients.

Diurnal Variation of Plasma Extracellular Vesicle Is Disrupted in People Living with HIV

BACKGROUND

Several types of extracellular vesicles (EVs) secreted by various immune and non-immune cells are present in the human plasma. We previously demonstrated that EV abundance and microRNA content change in pathological conditions, such as HIV infection. Here, we investigated daily variations of large and small EVs, in terms of abundance and microRNA contents in people living with HIV (PLWH) receiving antiretroviral therapy (HIV+ART) and uninfected controls (HIV-).

METHODS

Venous blood samples from n = 10 HIV+ART and n = 10 HIV- participants were collected at 10:00 and 22:00 the same day. Large and small plasma EVs were purified, counted, and the mature miRNAs miR-29a, miR-29b, miR-92, miR-155, and miR-223 copies were measured by RT-PCR.

RESULTS

Large EVs were significantly bigger in the plasma collected at 10:00 versus 22:00 in both groups. There was a significant day-night increase in the quantity of 5 miRNAs in HIV- large EVs. In HIV+ART, only miR-155 daily variation has been observed in large EVs. Finally, EV-miRNA content permits to distinguish HIV- to HIV+ART in multivariate analysis.

CONCLUSION

These results point that plasma EV amount and microRNA contents are under daily variation in HIV- people. This new dynamic measure is disrupted in PLWH despite viral-suppressive ART. This study highlights a significant difference concerning EV abundance and their content measured at 22:00 between both groups. Therefore, the time of blood collection must be considered in the future for the EV as biomarkers.

HIV-1 Vpr protein impairs lysosome clearance causing SNCA/alpha-synuclein accumulation in neurons

Despite the promising therapeutic effects of combinatory antiretroviral therapy (cART), 20% to 30% of HIV/AIDS patients living with long term infection still exhibit related cognitive and motor disorders. Clinical studies in HIV-infected patients revealed evidence of basal ganglia dysfunction, tremors, fine motor movement deficits, gait, balance, and increased risk of falls. Among older HIV⁺ adults, the frequency of cases with SNCA/α-synuclein staining is higher than in older healthy persons and may predict an increased risk of developing a neurodegenerative disease. The accumulation of SNCA aggregates known as Lewy Bodies is widely described to be directly linked to motor dysfunction. These aggregates are naturally removed by Macroautophagy/autophagy, a cellular housekeeping mechanism, that can be disturbed by HIV-1. The molecular mechanisms involved in linking HIV-1 proteins and autophagy remain mostly unclear and necessitates further exploration. We showed that HIV-1 Vpr protein triggers the accumulation of SNCA in neurons after decreasing lysosomal acidification, deregulating lysosome positioning, and the expression levels of several proteins involved in lysosomal maturation. Viruses and retroviruses such as HIV-1 are known to manipulate autophagy in order to use it for their replication while blocking the degradative final step, which could destroy the virus itself. Our study highlights how the suppression of neuronal autophagy by HIV-1 Vpr is a mechanism leading to toxic protein aggregation and neurodegeneration.Abbreviations: BLOC1: Biogenesis of Lysosome-related Organelles Complex 1; CART: combinatory antiretroviral therapy; CVB: coxsackievirus; DAPI: 4',6-diamidino-2-phenylindole; DENV: dengue virus; GFP: green fluorescent protein; HCV: hepatitis C virus; HCMV: human cytomegalovirus; HIV: human immunodeficiency virus; Env: HIV-1 envelope glycoproteins; GAPDH: glyceraldehyde-3-phosphate dehydrogenase; VSV: Indiana vesiculovirus; LTR: Long Terminal Repeat; LAMP1: lysosomal associated membrane protein 1; MAP1LC3B/LC3B: microtubule associated protein 1 light chain 3 beta; MLBs: multilamellar bodies; RIPA: Radioimmunoprecipitation assay buffer; SDS-PAGE: sodium dodecyl sulfate-polyacrylamide gel electrophoresis; Tat: transactivator of TAR; TEM: transmission electron microscope; Vpr: Viral protein R.

Effects of combination antiretroviral drugs (cART) on hippocampal neuroplasticity in female mice

The incidence of HIV-associated neurocognitive disorder (HAND) continues despite the introduction of combination antiretroviral drugs (cART). Several studies have reported the neurotoxicity of individual antiretroviral drugs (monotherapy), while the common approach for HIV treatment is through cART. Hence, the current study investigated the effects of long-term exposure to cART on cognitive function, oxidative damage, autophagy, and neuroplasticity in the hippocampus of mice. Female Balb/c mice received a once-a-day oral dose of cART composed of emtricitabine + tenofovir disoproxil fumarate or vehicle for 8 weeks. On week 7 of drug administration, all mice were assessed for spatial learning in the Morris water maze (MWM), and then on week 8, mice were sacrificed, and hippocampal tissue dissected from the brain. For biochemical analyses, we measured the concentration of 4-hydroxynonenal, and the expression of autophagic marker LC3B, synaptophysin, and brain-derived neurotrophic factor (BDNF) in the hippocampus. Our results showed that cART exposure increased escape latency in the MWM test. The cART-treated mice also showed increased 4-hydroxynonenal concentration and expression of LC3B. Furthermore, cART treatment decreased the expression of synaptophysin and BDNF. These findings further support the evidence that cART may be neurotoxic and therefore may play a role in the neuropathogenesis of HAND.

αB-Crystallin Alleviates Endotoxin-Induced Retinal Inflammation and Inhibits Microglial Activation and Autophagy

αB-Crystallin, a member of the small heat shock protein (sHSP) family, plays an immunomodulatory and neuroprotective role by inhibiting microglial activation in several diseases. However, its effect on endotoxin-induced uveitis (EIU) is unclear. Autophagy may be associated with microglial activation, and αB-crystallin is involved in the regulation of autophagy in some cells. The role of αB-crystallin in microglial autophagy is unknown. This study aimed to explore the role of αB-crystallin on retinal microglial autophagy, microglial activation, and neuroinflammation in both cultured BV2 cells and the EIU mouse model. Our results show that αB-crystallin reduced the release of typical proinflammatory cytokines at both the mRNA and protein level, inhibited microglial activation in morphology, and suppressed the expression of autophagy-related molecules and the number of autophagolysosomes in vitro. In the EIU mouse model, αB-crystallin treatment alleviated the release of ocular inflammatory cytokines and the representative signs of inflammation, reduced the apoptosis of ganglion cells, and rescued retinal inflammatory structural and functional damage, as evaluated by optical coherence tomographic and electroretinography. Taken together, these results indicate that αB-crystallin inhibits the activation of microglia and supresses microglial autophagy, ultimately reducing endotoxin-induced neuroinflammation. In conclusion, αB-crystallin provides a novel and promising option for affecting microglial autophagy and alleviating symptoms of ocular inflammatory diseases.

Autophagy-enhancing drugs limit mucosal HIV-1 acquisition and suppress viral replication ex vivo

Current direct-acting antiviral therapies are highly effective in suppressing HIV-1 replication. However, mucosal inflammation undermines prophylactic treatment efficacy, and HIV-1 persists in long-lived tissue-derived dendritic cells (DCs) and CD4+ T cells of treated patients. Host-directed strategies are an emerging therapeutic approach to improve therapy outcomes in infectious diseases. Autophagy functions as an innate antiviral mechanism by degrading viruses in specialized vesicles. Here, we investigated the impact of pharmaceutically enhancing autophagy on HIV-1 acquisition and viral replication. To this end, we developed a human tissue infection model permitting concurrent analysis of HIV-1 cellular targets ex vivo. Prophylactic treatment with autophagy-enhancing drugs carbamazepine and everolimus promoted HIV-1 restriction in skin-derived CD11c+ DCs and CD4+ T cells. Everolimus also decreased HIV-1 susceptibility to lab-adapted and transmitted/founder HIV-1 strains, and in vaginal Langerhans cells. Notably, we observed cell-specific effects of therapeutic treatment. Therapeutic rapamycin treatment suppressed HIV-1 replication in tissue-derived CD11c+ DCs, while all selected drugs limited viral replication in CD4+ T cells. Strikingly, both prophylactic and therapeutic treatment with everolimus or rapamycin reduced intestinal HIV-1 productive infection. Our findings highlight host autophagy pathways as an emerging target for HIV-1 therapies, and underscore the relevancy of repurposing clinically-approved autophagy drugs to suppress mucosal HIV-1 replication.

Human TRIM5α: Autophagy Connects Cell-Intrinsic HIV-1 Restriction and Innate Immune Sensor Functioning

Human immunodeficiency virus-1 (HIV-1) persists as a global health concern, with an incidence rate of approximately 2 million, and estimated global prevalence of over 35 million. Combination antiretroviral treatment is highly effective, but HIV-1 patients that have been treated still suffer from chronic inflammation and residual viral replication. It is therefore paramount to identify therapeutically efficacious strategies to eradicate viral reservoirs and ultimately develop a cure for HIV-1. It has been long accepted that the restriction factor tripartite motif protein 5 isoform alpha (TRIM5α) restricts HIV-1 infection in a species-specific manner, with rhesus macaque TRIM5α strongly restricting HIV-1, and human TRIM5α having a minimal restriction capacity. However, several recent studies underscore human TRIM5α as a cell-dependent HIV-1 restriction factor. Here, we present an overview of the latest research on human TRIM5α and propose a novel conceptualization of TRIM5α as a restriction factor with a varied portfolio of antiviral functions, including mediating HIV-1 degradation through autophagy- and proteasome-mediated mechanisms, and acting as a viral sensor and effector of antiviral signaling. We have also expanded on the protective antiviral roles of autophagy and outline the therapeutic potential of autophagy modulation to intervene in chronic HIV-1 infection.

Targeting Beclin1 as an Adjunctive Therapy against HIV Using Mannosylated Polyethylenimine Nanoparticles

Using nanoparticle-based RNA interference (RNAi), we have previously shown that silencing the host autophagic protein, Beclin1, in HIV-infected human microglia and astrocytes restricts HIV replication and its viral-associated inflammatory responses. Here, we confirmed the efficacy of Beclin1 small interfering RNA (siBeclin1) as an adjunctive antiviral and anti-inflammatory therapy in myeloid human microglia and primary human astrocytes infected with HIV, both with and without exposure to combined antiretroviral (cART) drugs. To specifically target human microglia and human astrocytes, we used a nanoparticle (NP) comprised of linear cationic polyethylenimine (PEI) conjugated with mannose (Man) and encapsulated with siBeclin1. The target specificity of the PEI-Man NP was confirmed in vitro using human neuronal and glial cells transfected with the NP encapsulated with fluorescein isothiocyanate (FITC). PEI-Man-siBeclin1 NPs were intranasally delivered to healthy C57BL/6 mice in order to report the biodistribution of siBeclin1 in different areas of the brain, measured using stem-loop RT-PCR. Postmortem brains recovered at 1–48 h post-treatment with the PEI-Man-siRNA NP showed no significant changes in the secretion of the chemokines regulated on activation, normal T cell expressed and secreted (RANTES) and monocyte chemotactic protein-1 (MCP-1) and showed significant decreases in the secretion of the cytokines interleukin 6 (IL-6) and tumor necrosis factor alpha (TNF-α) when compared to phosphate-buffered saline (PBS)-treated brains. Nissl staining showed minimal differences between the neuronal structures when compared to PBS-treated brains, which correlated with no adverse behavioral affects. To confirm the brain and peripheral organ distribution of PEI-siBeclin1 in living mice, we used the In vivo Imaging System (IVIS) and demonstrated a significant brain accumulation of siBeclin1 through intranasal administration.

N-Acetylcysteine Reverses Antiretroviral-Mediated Microglial Activation by Attenuating Autophagy-Lysosomal Dysfunction

Successful suppression of viral replication by combined antiretroviral therapy (cART) in HIV-1 infected individuals is paradoxically also accompanied by an increased prevalence of HIV-associated neurocognitive disorders (HAND) in these individuals. HAND is characterized by a state of chronic oxidative stress and inflammation. Microglia are extremely sensitive to a plethora of stimuli, including viral proteins and cART. The current study aimed to assess the effects of cART-mediated oxidative stress on the induction of inflammatory responses in microglia. In the present study, we chose a combination of three commonly used antiretroviral drugs—tenofovir disoproxil fumarate, emtricitabine, and dolutegravir. We demonstrated that exposure of microglia to the chosen cART cocktail induced generation of reactive oxygen species, subsequently leading to lysosomal dysfunction and dysregulated autophagy, ultimately resulting in the activation of microglia. Intriguingly, the potent antioxidant, N-acetylcysteine, reversed the damaging effects of cART. These in vitro findings were further corroborated in vivo wherein cART-treated HIV transgenic (Tg) rats demonstrated increased microglial activation, exaggerated lysosome impairment, and dysregulated autophagy in the prefrontal cortices compared with HIV Tg rats not exposed to cART. Similar to in vitro findings, the treatment of HIV Tg rats with N-acetylcysteine also mitigated the deleterious effects of cART. Taken together, our findings suggest that oxidative stress-mediated lysosomal dysfunction plays a critical role in the pathogenesis of HAND in drug-treated HIV-infected individuals and that antioxidant-mediated mitigation of oxidative stress could thus be considered as an adjunctive therapeutic strategy for ameliorating/dampening some of the neurological complications of HAND.

HIV Nef and Antiretroviral Therapy Have an Inhibitory Effect on Autophagy in Human Astrocytes that May Contribute to HIV-Associated Neurocognitive Disorders

A significant number of people living with HIV (PLWH) develop HIV-associated neurocognitive disorders (HAND) despite highly effective antiretroviral therapy (ART). Dysregulated macroautophagy (autophagy) is implicated in HAND pathogenesis. The viral protein Nef, expressed even with suppressive ART, and certain antiretrovirals affect autophagy in non-CNS cells. Astrocytes, vital for CNS microenvironment homeostasis and neuronal health, require autophagy for their own homeostasis. We hypothesized that extracellular Nef and/or ART impact astrocyte autophagy, thus contributing to HAND. We studied in-bulk and selective autophagic flux in primary human astrocytes treated with extracellular Nef and/or a combination of tenofovir+emtricitabine+raltegravir (ART) using Western blotting, a tandem fluorescent LC3 reporter, and transmission electron microscopy/morphometry. We show that after 24 h treatment, Nef and ART decrease autophagosomes through different mechanisms. While Nef accelerates autophagosome degradation without inducing autophagosome formation, ART inhibits autophagosome formation. Combination Nef+ART further depletes autophagosomes by inducing both abnormalities. Additionally, extracellular Nef and/or ART inhibit lysosomal degradation of p62, indicating Nef and/or ART affect in-bulk and selective autophagy differently. Dysregulation of both autophagic processes is maintained after 7 days of Nef and/or ART treatment. Persistent autophagy dysregulation due to chronic Nef and/or ART exposure may ultimately result in astrocyte and neuronal dysfunction, contributing to HAND.

Ultramicronized Palmitoylethanolamide and Paracetamol, a New Association to Relieve Hyperalgesia and Pain in a Sciatic Nerve Injury Model in Rat

Inflammation is known to be an essential trigger of the pathological changes that have a critical impact on nerve repair and regeneration; moreover, damage to peripheral nerves can cause a loss of sensory function and produces persistent neuropathic pain. To date, various potential approaches for neuropathic pain have focused on controlling neuroinflammation. The aim of this study was to investigate the neuroprotective effects of a new association of ultramicronized Palmitoylethanolamide (PEAum), an Autacoid Local Injury Antagonist Amide (ALIAmide) with analgesic and anti-inflammatory properties, with Paracetamol, a common analgesic, in a rat model of sciatic nerve injury (SNI). The association of PEAum-Paracetamol, in a low dose (5 mg/kg + 30 mg/kg), was given by oral gavage daily for 14 days after SNI. PEAum-Paracetamol association was able to reduce hyperalgesia, mast cell activation, c-Fos and nerve growth factor (NGF) expression, neural histological damage, cytokine release, and apoptosis. Furthermore, the analgesic action of PEAum-Paracetamol could act in a synergistic manner through the inhibition of the NF-κB pathway, which leads to a decrease of cyclooxygenase 2-dependent prostaglandin E₂ (COX-2/PGE₂) release. In conclusion, we demonstrated that PEAum associated with Paracetamol was able to relieve pain and neuroinflammation after SNI in a synergistic manner, and this therapeutic approach could be relevant to decrease the demand of analgesic drugs.

Pathogenesis of age-related HIV neurodegeneration

People over the age of 50 are the fastest growing segment of the HIV-infected population in the USA. Although antiretroviral therapy has remarkable success controlling the systemic HIV infection, HIV-associated neurocognitive disorder (HAND) prevalence has increased or remained the same among this group, and cognitive deficits appear more severe in aged patients with HIV. The mechanisms of HAND in the aged population are not completely understood; a leading hypothesis is that aged individuals with HIV might be at higher risk of developing Alzheimer's disease (AD) or one of the AD-related dementias (ADRD). There are a number of mechanisms through which chronic HIV disease alone or in combination with antiretroviral therapy and other comorbidities (e.g., drug use, hepatitis C virus (HCV)) might be contributing to HAND in individuals over the age of 50 years, including (1) overlapping pathogenic mechanisms between HIV and aging (e.g., decreased proteostasis, DNA damage, chronic inflammation, epigenetics, vascular), which could lead to accelerated cellular aging and neurodegeneration and/or (2) by promoting pathways involved in AD/ADRD neuropathogenesis (e.g., triggering amyloid β, Tau, or α-synuclein accumulation). In this manuscript, we will review some of the potential common mechanisms involved and evidence in favor and against a role of AD/ADRD in HAND.

Antiretroviral-Mediated Microglial Activation Involves Dysregulated Autophagy and Lysosomal Dysfunction

In the era of combined antiretroviral therapy (cART), as infected individuals continue to have longer lifespans, there is also an increased prevalence of HIV-associated neurocognitive disorders (HAND). Inflammation is one of the underlying features of HAND, with the role of viral proteins and antiretroviral drugs implicated in this process. Microglia are extremely sensitive to a plethora of stimuli, including viral products and cART. The current study was undertaken to understand the molecular mechanism(s) underlying cART-mediated activation of microglia. Herein we chose a combination of three commonly used drugs, tenofovir disoproxil fumarate (TDF), emtricitabine (FTC), and dolutegravir (DTG). We demonstrated that exposure of microglia to this cART cocktail induced lysosomal membrane permeabilization (LMP), which subsequently resulted in impaired lysosomal functioning involving elevated pH and decreased cathepsin D (CTSD) activity. cART exposure of microglia resulted in increased formation of autophagosomes as demonstrated by a time-dependent increase of autophagy markers, with a concomitant defect in the fusion of the lysosomes with the autophagosome. Taken together, our findings suggest a novel mechanism by which cART impairs lysosomal functioning, resulting in dysregulated autophagy and increased neuroinflammation. Interventions aimed at lysosome protection could likely be envisioned as promising therapeutic targets for abrogating cART-mediated microglia activation, which in turn, could thus be considered as adjunctive therapeutics for the treatment of HAND pathogenesis.

Neuroinflammation & pre-mature aging in the context of chronic HIV infection and drug abuse: Role of dysregulated autophagy

In the era of combined antiretroviral therapy (cART), HIV-1 infection has transformed from adeath sentenceto a manageable, chronic disease. Although the lifeexpectancy of HIV+ individuals is comparable to that of the uninfectedsubjects paradoxically, there is increased prevalence ofage-associatedcomorbidities such asatherosclerosis, diabetes, osteoporosis & neurological deficits in the context of HIV infection. Drug abuse is a commoncomorbidityofHIV infection andis often associated withincreased neurological complications. Chronic neuroinflammation (abnormal microglial and astrocyte activation) and neuronal synaptodendritic injury are the features of CNS pathology observed inHIV (+) individualsthat are takingcART & that abuse drugs. Neuroinflammation is thedrivingforceunderlying prematureaging associated with HIV (+) infection, cART and drugs of abuse. Autophagy is a highly conserved process critical for maintaining cellular homeostasis. Dysregulated autophagyhas been shown to be linked with abnormal immune responses & aging. Recent emerging evidence implicatesthe role ofHIV/HIV proteins, cART, & abused drugsin disrupting theautophagy process in brain cells such as microglia, astrocytes, and neurons. It can thus be envisioned that co-exposure of CNS cells to HIV proteins, cART and/or abused drugs couldhavesynergistic effects on theautophagy process, thereby leading to exaggerated microglial/astrocyte activation, ultimately, promotingthe aging process. Restoration of autophagic functioncould thusprovide an alternative therapeuticstrategy formitigating neuroinflammation & ameliorating the premature aging process. The current review aims to unravel the role of dysregulated autophagy in the context of single or co-exposure of microglia, astrocytes, and neurons to HIV/HIV proteins, drugs of abuse &/or cART and will also discuss the pathways involved in dysregulated autophagy-mediated neuroinflammation.

Involvement of organelles and inter-organellar signaling in the pathogenesis of HIV-1 associated neurocognitive disorder and Alzheimer's disease

Endolysosomes, mitochondria, peroxisomes, endoplasmic reticulum, and plasma membranes are now known to physically and functionally interact with each other. Such findings of inter-organellar signaling and communication has led to a resurgent interest in cell biology and an increased appreciation for the physiological actions and pathological consequences of the dynamic physical and chemical communications occurring between intracellular organelles. Others and we have shown that HIV-1 proteins implicated in the pathogenesis of neuroHIV and that Alzheimer's disease both affects the structure and function of intracellular organelles. Intracellular organelles are highly mobile, and their intracellular distribution almost certainly affects their ability to interact with other organelles and to regulate such important physiological functions as endolysosome acidification, cell motility, and nutrient homeostasis. Indeed, compounds that acidify endolysosomes cause endolysosomes to exhibit a mainly perinuclear pattern while compounds that de-acidify endolysosomes cause these organelles to exhibit a larger profile as well as movement towards plasma membranes. Endolysosome pH might be an early event in the pathogenesis of neuroHIV and Alzheimer's disease and in terms of organellar biology endolysosome changes might be upstream of HIV-1 protein-induced changes to other organelles. Thus, inter-organellar signaling mechanisms might be involved in the pathogenesis of neuroHIV and other neurological disorders, and a better understanding of inter-organellar signaling might lead to improved therapeutic strategies.

Selective cell death of latently HIV-infected CD4+ T cells mediated by autosis inducing nanopeptides

Despite significant advances in the treatment of human immunodeficiency virus type-1 (HIV) infection, antiretroviral therapy only suppresses viral replication but is unable to eliminate infection. Thus, discontinuation of antiretrovirals results in viral reactivation and disease progression. A major reservoir of HIV latent infection resides in resting central memory CD4+ T cells (TCM) that escape clearance by current therapeutic regimens and will require novel strategies for elimination. Here, we evaluated the therapeutic potential of autophagy-inducing peptides, Tat-Beclin 1 and Tat-vFLIP-α2, which can induce a novel Na+/K+-ATPase dependent form of cell death (autosis), to kill latently HIV-infected TCM while preventing virologic rebound. In this study, we encapsulated autophagy inducing peptides into biodegradable lipid-coated hybrid PLGA (poly lactic-co-glycolic acid) nanoparticles for controlled intracellular delivery. A single dose of nanopeptides was found to eliminate latent HIV infection in an in vitro primary model of HIV latency and ex vivo using resting CD4+ T cells obtained from peripheral blood mononuclear cells of HIV-infected patients on antiretroviral with fully suppressed virus for greater than 12 months. Notably, increased LC3B lipidation, SQSTM1/p62 degradation and Na+/K+-ATPase activity characteristic of autosis, were detected in nanopeptide treated latently HIV-infected cells compared to untreated uninfected or infected cells. Nanopeptide-induced cell death could be reversed by knockdown of autophagy proteins, ATG5 and ATG7, and inhibition or knockdown of Na+/K+-ATPase. Importantly, viral rebound was not detected following the induction of the Na+/K+-ATPase dependent form of cell death induced by the Tat-Beclin 1 and Tat-vFLIP-α2 nanopeptides. These findings provide a novel strategy to eradicate HIV latently infected resting memory CD4+ T cells, the major reservoir of HIV latency, through the induction of Na+/K+-ATPase dependent autophagy, while preventing reactivation of virus and new infection of uninfected bystander cells.

The Dual Role of HIV-1 gp120 V3 Loop-Induced Autophagy in the Survival and Apoptosis of the Primary Rat Hippocampal Neurons

HIV-1 gp120, an important subunit of the envelope spikes that decorate the surface of virions, is known to play a vital role in neuronal injury during HIV-1-associated neurocognitive disorder (HAND), although the pathological mechanism is not fully understood. Our previous studies have suggested that the V3 loop of HIV-1 gp120 (HIV-1 gp120 V3 loop) can induce neuronal apoptosis in the hippocampus, resulting in impairment in spatial learning and memory in Sprague-Dawley (SD) rats. In this study, we demonstrated that autophagy was significantly increased in rat primary hippocampal neurons in response to treatment of HIV-1 gp120 V3 loop. Importantly, HIV-1 gp120 V3 loop-induced autophagy played a dual role in the cell survival and death. An increase in autophagy for a short period inhibited apoptosis of neurons, while persistent autophagy over an extended period of time played a detrimental role by augmenting the apoptotic cascade in rat primary hippocampal neurons. In addition, we found that the HIV-1 gp120 V3 loop induced autophagy via AMPK/mTOR-dependent and calpain/mTOR-independent pathways, and the ERK/mTOR pathway plays a partial role. These findings provide evidence that HIV-1-induced autophagy plays a dual role in the survival and apoptosis of the primary rat hippocampal neurons and persistent autophagy may contribute to the pathogenesis of HAND, and autophagy modulation may represent a potential therapeutic strategy for reducing neuronal damage in HAND.

Autophagy Intertwines with Different Diseases-Recent Strategies for Therapeutic Approaches

Autophagy is a regular and substantial “clear-out process” that occurs within the cell and that gets rid of debris that accumulates in membrane-enclosed vacuoles by using enzyme-rich lysosomes, which are filled with acids that degrade the contents of the vacuoles. This machinery is well-connected with many prevalent diseases, including cancer, HIV, and Parkinson’s disease. Considering that autophagy is well-known for its significant connections with a number of well-known fatal diseases, a thorough knowledge of the current findings in the field is essential in developing therapies to control the progression rate of diseases. Thus, this review summarizes the critical events comprising autophagy in the cellular system and the significance of its key molecules in manifesting this pathway in various diseases for down- or upregulation. We collectively reviewed the role of autophagy in various diseases, mainly neurodegenerative diseases, cancer, inflammatory diseases, and renal disorders. Here, some collective reports on autophagy showed that this process might serve as a dual performer: either protector or contributor to certain diseases. The aim of this review is to help researchers to understand the role of autophagy-regulating genes encoding functional open reading frames (ORFs) and its connection with diseases, which will eventually drive better understanding of both the progression and suppression of different diseases at various stages. This review also focuses on certain novel therapeutic strategies which have been published in the recent years based on targeting autophagy key proteins and its interconnecting signaling cascades.

Alterations in brain TREM2 and Amyloid-β levels are associated with neurocognitive impairment in HIV-infected persons on antiretroviral therapy

Neuroinflammation is a common pathological correlate of HIV-associated neurocognitive disorders (HAND) in individuals on antiretroviral therapy (ART). Triggering receptor expressed on myeloid cells 2 (TREM2) regulates neuroinflammation, clears extracellular Amyloid (A)-β, surveys for damaged neurons, and orchestrates microglial differentiation. TREM2 has not been studied in HIV+ brain tissues. In this retrospective study, we investigated TREM2 expression levels and localization to microglia, Aβ protein levels, and tumor necrosis factor (TNF)-α transcript levels in the frontal cortices of 52 HIV+ decedents. All donors had been on ART; 14 were cognitively normal (CN), 17 had an asymptomatic neurocognitive impairment (ANI), and 21 had a minor neurocognitive disorder (MND). Total TREM2 protein levels were increased in the soluble and decreased in the membrane-enriched fractions of MND brain tissues compared to CN; however, brains from MND Hispanics showed the most robust alterations in TREM2 as well as significantly increased TNF-α mRNA and Aβ levels when compared to CN Hispanics. Significant alterations in the expression of total TREM2 protein and transcripts for TNF-α were not observed in non-Hispanics, despite higher levels of Aβ in the non-Hispanic CN group compared to the non-Hispanic MND groups. These findings show that decreased and increased TREM2 in membrane-bound fractions and in soluble-enriched fractions, respectively, is associated with increased Aβ and neuroinflammation in this cohort of HIV+ brains, particularly those identifying as Hispanics. These findings suggest a role for TREM2 in the brain of HIV+ individuals may deserve more investigation as a biomarker for HAND and as a possible therapeutic target. OPEN SCIENCE BADGES: This article has received a badge for *Open Materials* because it provided all relevant information to reproduce the study in the manuscript. The complete Open Science Disclosure form for this article can be found at the end of the article. More information about the Open Practices badges can be found at https://cos.io/our-services/open-science-badges/.

Autophagy, EVs, and Infections: A Perfect Question for a Perfect Time

Autophagy, a highly conserved process, serves to maintain cellular homeostasis in response to an extensive variety of internal and external stimuli. The classic, or canonical, pathway of autophagy involves the coordinated degradation and recycling of intracellular components and pathogenic material. Proper regulation of autophagy is critical to maintain cellular health, as alterations in the autophagy pathway have been linked to the progression of a variety of physiological and pathological conditions in humans, namely in aging and in viral infection. In addition to its canonical role as a degradative pathway, a more unconventional and non-degradative role for autophagy has emerged as an area of increasing interest. This process, known as secretory autophagy, is gaining widespread attention as many viruses are believed to use this pathway as a means to release and spread viral particles. Moreover, secretory autophagy has been found to intersect with other intracellular pathways, such as the biogenesis and secretion of extracellular vesicles (EVs). Here, we provide a review of the current landscape surrounding both degradative autophagy and secretory autophagy in relation to both aging and viral infection. We discuss their key features, while describing their interplay with numerous different viruses (i.e. hepatitis B and C viruses, Epstein-Barr virus, SV40, herpesviruses, HIV, chikungunya virus, dengue virus, Zika virus, Ebola virus, HTLV, Rift Valley fever virus, poliovirus, and influenza A virus), and compare secretory autophagy to other pathways of extracellular vesicle release. Lastly, we highlight the need for, and emphasize the importance of, more thorough methods to study the underlying mechanisms of these pathways to better advance our understanding of disease progression.

Effect of PEA-OXA on neuropathic pain and functional recovery after sciatic nerve crush

Background

Animal models of sciatic nerve injury are commonly used to study neuropathic pain as well as axon regeneration. Inflammation/immune response at the site of nerve lesion is known to be an essential trigger of the pathological changes that have a critical impact on nerve repair and regeneration; moreover, the damage to peripheral nerve can cause a loss of sensory function and produces a persistent neuropathic pain. N-Acylethanolamines (NAEs) involve a family of lipid molecules existent in animal and plant, of which is N-palmitoylethanolamide (PEA) that arouses great attention owing to its anti-inflammatory, analgesic, and neuroprotective activities. The modulation of specific amidases for NAEs (and in particular NAE-hydrolyzing acid amidase NAAA, which is more selective for PEA) could be a condition to preserve its levels. Here, we investigated, in a mice model of sciatic nerve crush, the effect of 2-pentadecyl-2-oxazoline (PEA-OXA) the oxazoline of PEA that reportedly modulates activity of NAAA.

Methods

In this experimental model, the mice, following the sciatic nerve crush, were treated daily with PEA-OXA at a dose of 10 mg\kg for 14 days. Therefore, we evaluated the effects of PEA-OXA on the degree of injury, on the inhibition of neuropathic pain, and on the inflammatory process, as in the improvement of reparative processes and therefore in the restoration of locomotor function.

Results

Our results showed that PEA-OXA (10 mg/kg) treatment, daily, for 14 days after sciatic nerve crush, have an anti-inflammatory and neuroprotective effect and moreover have an analgesic protective effect on hypersensitivity, and improve the functional recovery after nerve crush.

Conclusions

Therefore, treatment with PEA-OXA as a whole has shown a protective effect, which makes it a powerful candidate for the treatment of peripheral nerve injury and neuropathic pain.

HIV-1 Tat increases BAG3 via NF-κB signaling to induce autophagy during HIV-associated neurocognitive disorder

The human immunodeficiency virus-1 (HIV-1) regulatory protein Tat plays an important role during HIV-1-associated neurocognitive disorders (HAND) by inducing neuronal autophagy. In this study, we used immunohistochemistry, immunofluorescence, western blot, qRT-PCR, and RNA interference to elucidate the involvement of Bcl-2-associated athanogene 3 (BAG3) in the pathogenesis of HIV-1 Tat-induced autophagy during HAND. We found that BAG3 expression is elevated in astrocytes in frontal cortex of macaques infected with simian immunodeficiency virus-human immunodeficiency chimeric virus (SHIV). In addition, in human primary glioblastoma cells (U87), HIV-1 Tat upregulated BAG3 in an NF-κB-dependent manner to induce autophagy. Importantly, suppression of BAG3 or inhibition of NF-κB activity reversed the HIV-1 Tat-induced autophagy. These results indicate that HIV-1 Tat induces autophagy by upregulating BAG3 via NF-κB signaling, which suggests BAG3 and NF-κB could potentially serve as novel targets for HAND therapies.

Neuroprotective Effect of Artesunate in Experimental Model of Traumatic Brain Injury

Traumatic brain injuries (TBI) are an important public health challenge. In addition, subsequent events at TBI can compromise the quality of life of these patients. In fact, TBI is associated with several complications for both long and short term, some evidence shows how TBI is associated with a decline in cognitive functions such as the risk of developing dementia, cerebral atrophy, and Parkinson disease. After the direct damage from TBI, a key role in TBI injury is played by the inflammatory response and oxidative stress, that contributes to tissue damage and to neurodegenerative processes, typical of secondary injury, after TBI. Given the complex series of events that are involved after TBI injury, a multitarget pharmacological approach is needed. Artesunate is a more stable derivative of its precursor artemisin, a sesquiterpene lactone obtained from a Chinese plant Artemisia annua, a plant used for centuries in traditional Chinese medicine. artesunate has been shown to be a pluripotent agent with different pharmacological actions. therefore, in this experimental model of TBI we evaluated whether the treatment with artesunate at the dose of 30 mg\Kg, had an efficacy in reducing the neuroinflammatory process after TBI injury, and in inhibiting the NLRP3 inflammasome pathway, which plays a key role in the inflammatory process. We also assessed whether treatment with artesunate was able to exert a neuroprotective action by modulating the release of neurotrophic factors. our results show that artesunate was able to reduce the TBI-induced lesion, it also showed an anti-inflammatory action through the inhibition of Nf-kb, release of proinflammatory cytokines IL-1β and TNF-α and through the inhibition NLRP3 inflammasome complex, furthermore was able to reduce the activation of astrocytes and microglia (GFAP, Iba-1). Finally, our results show that the protective effects of artesunate also occur through the modulation of neurotrophic factors (BDNF, GDNF, NT-3) that play a key role in neuronal survival.

Induction of a Na+/K+-ATPase-dependent form of autophagy triggers preferential cell death of human immunodeficiency virus type-1-infected macrophages

Although antiretroviral therapy is highly effective in suppressing human immunodeficiency virus type-1 (HIV) replication, treatment has failed to eliminate viral reservoirs and discontinuation of treatment results in viral reactivation. Here, we demonstrate that peptides Tat-vFLIP-α2 and Tat-Beclin 1/BECN1 which have been shown to induce a Na⁺/K⁺-ATPase- and a macroautophagy/autophagy-dependent form of cell death, autosis, can preferentially kill HIV-infected macrophages while preventing virological rebound. To improve bioavailability and drug delivery, Tat-vFLIP-α2 was encapsulated into biodegradable PLGA (poly lactic-co-glycolic acid)-lipid-PEG (polyethylene glycol) nanoparticles for long-lasting intracellular delivery. After a single dose of NP-vFLIP-α2, HIV-infected macrophages were preferentially killed in a dose-dependent manner compared to uninfected or untreated HIV-infected cells with complete inhibition of HIV infection at 10 μM of peptide. HIV-infected macrophages treated with NP-vFLIP-α2 exhibited increased markers of autophagy including LC3B lipidation, SQSTM1/p62 degradation and Na⁺/K⁺-ATPase expression compared to untreated uninfected or infected cells. Moreover, the increased cell death observed in HIV-infected cells was not altered by treatment with bafilomycin A₁ (BAF) or the caspase inhibitor Z-VAD-FMK, but could be reversed following treatment with the Na⁺/K⁺-ATPase inhibitor, digoxin, or knockdown of ATG5 or ATG7. NP-vFLIP-α2 induced preferential killing was also detected in HIV-infected macrophages under antiretroviral suppression without inducing viral reactivation. Additionally, we found that Na⁺/K⁺-ATPase was upregulated in HIV-infected cells, which enhanced NP-vFLIP-α2 induced cell death. These findings provide a novel strategy to eradicate HIV-infected macrophages by selectively killing infected cells through the induction of Na⁺/K⁺-ATPase dependent autophagy, while preventing reactivation of virus and new infection of uninfected bystander cells.

Autophagy: The multi-purpose bridge in viral infections and host cells

Autophagy signaling pathway is involved in cellular homeostasis, developmental processes, cellular stress responses, and immune pathways. The aim of this review is to summarize the relationship between autophagy and viruses. It is not possible to be fully comprehensive, or to provide a complete "overview of all viruses". In this review, we will focus on the interaction of autophagy and viruses and survey how human viruses exploit multiple steps in the autophagy pathway to help viral propagation and escape immune response. We discuss the role that macroautophagy plays in cells infected with hepatitis C virus, hepatitis B virus, rotavirus gastroenteritis, immune cells infected with human immunodeficiency virus, and viral respiratory tract infections both influenza virus and coronavirus.

An Overview of Human Immunodeficiency Virus Type 1-Associated Common Neurological Complications: Does Aging Pose a Challenge?

With increasing survival of patients infected with human immunodeficiency virus type 1 (HIV-1), the manifestation of heterogeneous neurological complications is also increasing alarmingly in these patients. Currently, more than 30% of about 40 million HIV-1 infected people worldwide develop central nervous system (CNS)-associated dysfunction, including dementia, sensory, and motor neuropathy. Furthermore, the highly effective antiretroviral therapy has been shown to increase the prevalence of mild cognitive functions while reducing other HIV-1-associated neurological complications. On the contrary, the presence of neurological disorder frequently affects the outcome of conventional HIV-1 therapy. Although, both the children and adults suffer from the post-HIV treatment-associated cognitive impairment, adults, especially depending on the age of disease onset, are more prone to CNS dysfunction. Thus, addressing neurological complications in an HIV-1-infected patient is a delicate balance of several factors and requires characterization of the molecular signature of associated CNS disorders involving intricate cross-talk with HIV-1-derived neurotoxins and other cellular factors. In this review, we summarize some of the current data supporting both the direct and indirect mechanisms, including neuro-inflammation and genome instability in association with aging, leading to CNS dysfunction after HIV-1 infection, and discuss the potential strategies addressing the treatment or prevention of HIV-1-mediated neurotoxicity.

Implication of Different HIV-1 Genes in the Modulation of Autophagy

Autophagy is a complex cellular degradation pathway, which plays important roles in the regulation of several developmental processes, cellular stress responses, and immune responses induced by pathogens. A number of studies have previously demonstrated that HIV-1 was capable of altering the regulation of autophagy and that this biological process could be induced in uninfected and infected cells. Furthermore, previous reports have indicated that the involvement of HIV-1 in autophagy regulation is a complex phenomenon and that different viral proteins are contributing in its modulation upon viral infection. Herein, we review the recent literature over the complex crosstalk of the autophagy pathway and HIV-1, with a particular focus on HIV-1 viral proteins, which have been shown to modulate autophagy.

Transgenic mice expressing HIV-1 envelope protein gp120 in the brain as an animal model in neuroAIDS research

HIV-1 infection causes injury to the central nervous system (CNS) and is often associated with neurocognitive disorders. One model for brain damage seen in AIDS patients is the transgenic (tg) mouse expressing a soluble envelope protein gp120 of HIV-1 LAV in the brain in astrocytes under the control of the promoter of glial fibrillary acidic protein. These GFAP-gp120tg mice manifest several key neuropathological features observed in AIDS brains, such as decreased synaptic and dendritic density, increased numbers of activated microglia, and pronounced astrocytosis. Several recent studies show that brains of GFAP-gp120tg mice and neurocognitively impaired HIV patients share also a significant number of differentially regulated genes, activation of innate immunity and other cellular signaling pathways, disturbed neurogenesis, and learning deficits. These findings support the continued relevance of the GFAP-gp120tg mouse as a useful model to investigate neurodegenerative mechanisms and develop therapeutic strategies to mitigate the consequences associated with HIV infection of the CNS, neuroAIDS, and HAND.

Canonical and Non-Canonical Autophagy in HIV-1 Replication Cycle

Autophagy is a lysosomal-dependent degradative process essential for maintaining cellular homeostasis, and is a key player in innate and adaptive immune responses to intracellular pathogens such as human immunodeficiency virus type 1 (HIV-1). In HIV-1 target cells, autophagy mechanisms can (i) selectively direct viral proteins and viruses for degradation; (ii) participate in the processing and presentation of viral-derived antigens through major histocompatibility complexes; and (iii) contribute to interferon production in response to HIV-1 infection. As a consequence, HIV-1 has evolved different strategies to finely regulate the autophagy pathway to favor its replication and dissemination. HIV-1 notably encodes accessory genes encoding Tat, Nef and Vpu proteins, which are able to perturb and hijack canonical and non-canonical autophagy mechanisms. This review outlines the current knowledge on the complex interplay between autophagy and HIV-1 replication cycle, providing an overview of the autophagy-mediated molecular processes deployed both by infected cells to combat the virus and by HIV-1 to evade antiviral response.

Interplay between Autophagy, Exosomes and HIV-1 Associated Neurological Disorders: New Insights for Diagnosis and Therapeutic Applications

The autophagy–lysosomal pathway mediates a degradative process critical in the maintenance of cellular homeostasis as well as the preservation of proper organelle function by selective removal of damaged proteins and organelles. In some situations, cells remove unwanted or damaged proteins and RNAs through the release to the extracellular environment of exosomes. Since exosomes can be transferred from one cell to another, secretion of unwanted material to the extracellular environment in exosomes may have an impact, which can be beneficial or detrimental, in neighboring cells. Exosome secretion is under the influence of the autophagic system, and stimulation of autophagy can inhibit exosomal release and vice versa. Neurons are particularly vulnerable to degeneration, especially as the brain ages, and studies indicate that imbalances in genes regulating autophagy are a common feature of many neurodegenerative diseases. Cognitive and motor disease associated with severe dementia and neuronal damage is well-documented in the brains of HIV-infected individuals. Neurodegeneration seen in the brain in HIV-1 infection is associated with dysregulation of neuronal autophagy. In this paradigm, we herein provide an overview on the role of autophagy in HIV-associated neurodegenerative disease, focusing particularly on the effect of autophagy modulation on exosomal release of HIV particles and how this interplay impacts HIV infection in the brain. Specific autophagy–regulating agents are being considered for therapeutic treatment and prevention of a broad range of human diseases. Various therapeutic strategies for modulating specific stages of autophagy and the current state of drug development for this purpose are also evaluated.

Basic science and pathogenesis of ageing with HIV: potential mechanisms and biomarkers

: The increased prevalence of age-related comorbidities and mortality is worrisome in ageing HIV-infected patients. Here, we aim to analyse the different ageing mechanisms with regard to HIV infection. Ageing results from the time-dependent accumulation of random cellular damage. Epigenetic modifications and mitochondrial DNA haplogroups modulate ageing. In antiretroviral treatment-controlled patients, epigenetic clock appears to be advanced, and some haplogroups are associated with HIV infection severity. Telomere shortening is enhanced in HIV-infected patients because of HIV and some nucleoside analogue reverse transcriptase inhibitors. Mitochondria-related oxidative stress and mitochondrial DNA mutations are increased during ageing and also by some nucleoside analogue reverse transcriptase inhibitors. Overall, increased inflammation or 'inflammageing' is a major driver of ageing and could result from cell senescence with secreted proinflammatory mediators, altered gut microbiota, and coinfections. In HIV-infected patients, the level of inflammation and innate immunity activation is enhanced and related to most comorbidities and to mortality. This status could result, in addition to age, from the virus itself or viral protein released from reservoirs, from HIV-enhanced gut permeability and dysbiosis, from antiretroviral treatment, from frequent cytomegalovirus and hepatitis C virus coinfections, and also from personal and environmental factors, as central fat accumulation or smoking. Adaptive immune activation and immunosenescence are associated with comorbidities and mortality in the general population but are less predictive in HIV-infected patients. Biomarkers to evaluate ageing in HIV-infected patients are required. Numerous systemic or cellular inflammatory, immune activation, oxidative stress, or senescence markers can be tested in serum or peripheral blood mononuclear cells. The novel European Study to Establish Biomarkers of Human Ageing MARK-AGE algorithm, evaluating the biological age, is currently assessed in HIV-infected patients and reveals an advanced biological age. Some enhanced inflammatory or innate immune activation markers are interesting but still not validated for the patient's follow-up. To be able to assess patients' biological age is an important objective to improve their healthspan.

Role of autophagy in HIV infection and pathogenesis

The aim of autophagy is to re-establish homeostasis in response to a variety of stress conditions. By forming double-membrane vesicles, autophagy engulfs damaged or superfluous cytoplasmic material and recycles degradation products for new synthesis or energy production. Of note, the same mechanism is used to capture pathogens and has important implications in both innate and adaptive immunity. To establish a chronic infection, pathogens have therefore evolved multiple mechanisms to evade autophagy-mediated degradation. HIV infection represents one of the best characterized systems in which autophagy is disarmed by a virus using multiple strategies to prevent the sequestration and degradation of its proteins and to establish a chronic infection. HIV alters autophagy at various stages of the process in both infected and bystander cells. In particular, the HIV proteins TAT, NEF and ENV are involved in this regulation by either blocking or stimulating autophagy through direct interaction with autophagy proteins and/or modulation of the mTOR pathway. Although the roles of autophagy during HIV infection are multiple and vary amongst the different cell types, several lines of evidence point to a potential beneficial effect of stimulating autophagy-mediated lysosomal degradation to potentiate the immune response to HIV. Characterization of the molecular mechanisms regulating selective autophagy is expected to be valuable for developing new drugs able to specifically enhance the anti-HIV response.

The anticancer drug sunitinib promotes autophagyand protects from neurotoxicity in an HIV-1 Tat model of neurodegeneration

Despite the success of antiretroviral therapies to control systemic HIV-1 infection, the prevalence of HIV-associated neurocognitive disorders (HANDs) has not decreased among aging patients with HIV. Autophagy pathway alterations, triggered by HIV-1 proteins including gp120, Tat, and Nef, might contribute to the neurodegenerative process in aging patients with HAND. Although no treatments are currently available to manage HAND, we have previously shown that sunitinib, an anticancer drug that blocks receptor tyrosine-kinase and cyclin kinase pathways, might be of interest. Studies in cancer models suggest that sunitinib might also modulate autophagy, which is dysregulated in our models of Tat-induced neurotoxicity. We evaluated the efficacy of sunitinib to promote autophagy in the CNS and ameliorate neurodegeneration using LC3-GFP-expressing neuronal cells challenged with low concentrations of Tat and using inducible Tat transgenic mice. In neuronal cultures challenged with low levels of Tat, sunitinib increased markers of autophagy such as LC3-II and reduced p62 accumulation in a dose-dependent manner. In vivo, sunitinib treatment restored LC3-II, p62, and endophilin B1 (EndoB1) levels in doxycycline-induced Tat transgenic mice. Moreover, in these animals, sunitinib reduced the hyperactivation of CDK5, tau hyperphosphorylation, and p35 cleavage to p25. Restoration of CDK5 and autophagy were associated with reduced neurodegeneration and behavioral alterations. Alterations in autophagy in the Tat tg mice were associated with reduced levels of a CDK5 substrate, EndoB1, and levels of total EndoB1 were normalized by sunitinib treatment. We conclude that sunitinib might ameliorate Tat-mediated autophagy alterations and may decrease neurodegeneration in aging patients with HAND.

ASPP2 Plays a Dual Role in gp120-Induced Autophagy and Apoptosis of Neuroblastoma Cells

HIV invasion of the central nervous system (CNS) in the majority of patients infected with HIV-1, leads to dysfunction and injury within the CNS, showing a variety of neurological symptoms which was broadly termed HIV-associated neurocognitive disorder (HAND). But the molecular mechanisms are not completely understood. It has been suggested that apoptosis and autophagic dysfunction in neurons may play an important role in the development of HAND. Previous studies have indicated that p53 may be involved in the onset of neurological disorder in AIDS. Apoptosis-stimulating protein of p53-2 (ASPP2), a p53-binding protein with specific function of inducing p53, has been reported to modulate autophagy. In the present study, we observed that gp120 induces autophagy and apoptosis in SH-SY5Y neuroblastoma cells. Adenovirus-mediated overexpression of ASPP2 significantly inhibited autophagy and apoptosis induced by low dose of gp120 protein (50 ng/mL), but induced autophagy and apoptosis when treated by high dose of gp120 protein (200 ng/mL). Further, ASPP2 knockdown attenuated autophagy and apoptosis induced by gp120.

Conclusion: ASPP2 had different effects on the autophagy and apoptosis of neurons induced by different concentration of gp120 protein. It may be a potential therapeutic agent for HAND through modulating autophagy and apoptosis in CNS.

Interplay of endoplasmic reticulum stress and autophagy in neurodegenerative disorders

The common underlying feature of most neurodegenerative diseases such as Alzheimer disease (AD), prion diseases, Parkinson disease (PD), and amyotrophic lateral sclerosis (ALS) involves accumulation of misfolded proteins leading to initiation of endoplasmic reticulum (ER) stress and stimulation of the unfolded protein response (UPR). Additionally, ER stress more recently has been implicated in the pathogenesis of HIV-associated neurocognitive disorders (HAND). Autophagy plays an essential role in the clearance of aggregated toxic proteins and degradation of the damaged organelles. There is evidence that autophagy ameliorates ER stress by eliminating accumulated misfolded proteins. Both abnormal UPR and impaired autophagy have been implicated as a causative mechanism in the development of various neurodegenerative diseases. This review highlights recent advances in the field on the role of ER stress and autophagy in AD, prion diseases, PD, ALS and HAND with the involvement of key signaling pathways in these processes and implications for future development of therapeutic strategies.

Methamphetamine potentiates HIV-1 gp120-mediated autophagy via Beclin-1 and Atg5/7 as a pro-survival response in astrocytes

Methamphetamine (METH), a commonly used controlled substance, is known to exacerbate neuropathological dysfunction in HIV-infected individuals. The neuropathological manifestation results from cell death or dysfunction in the central nervous system (CNS) wherein autophagy is expected to have an important role. Autophagy is generally considered protective during deprivation/stress. However, excessive autophagy can be destructive, leading to autophagic cell death. This study was designed to investigate if METH and HIV-1 gp120 interact to induce autophagy in SVGA astrocytes, and whether autophagy is epiphenomenal or it has a role in METH- and gp120-induced cytotoxicity. We found that METH and gp120 IIIb caused an increase in LC3II level in astrocytes in a dose- and time-dependent manner, and the level of LC3II was further increased when the cells were treated with METH and gp120 IIIb in combination. Next, we sought to explore the mechanism by which METH and gp120 induce the autophagic response. We found that METH induces autophagy via opioid and metabotropic glutamate receptor type 5 (mGluR5) receptors. Other than that, signaling proteins Akt, mammalian target of rapamycin (mTOR), Beclin-1, Atg5 and Atg7 were involved in METH and gp120-mediated autophagy. In addition, long-term treatment of METH and gp120 IIIb resulted in cell death, which was exacerbated by inhibition of autophagy. This suggests that autophagy functions as a protective response against apoptosis caused by METH and gp120. This study is novel and clinically relevant because METH abuse among HIV-infected populations is highly prevalent and is known to cause exacerbated neuroAIDS.

Traumatic Brain Injury Leads to Development of Parkinson's Disease Related Pathology in Mice

Traumatic brain injury (TBI) is a major health and socio-economic problem that affects all societies. This condition results from the application of external physical strength to the brain that leads to transitory or permanent structural and functional impairments. Moreover, TBI is a risk factor for neurodegeneration and can e.g., increase the risk for Parkinson's disease (PD), a late-onset neurodegenerative disorder with loss of dopaminergic neurons in substantia nigra. In this study, we wanted to explore the possible development of PD-related pathology within the context of an experimental model of TBI. Traumatic brain injury was induced in mice by controlled cortical impact. At different time points behavioral tests (open field, elevated plus maze tests, and Barnes maze) were performed: The animals were sacrificed 30 days after the impact and the brains were processed for Western blot and immunohistochemical analyses. Following TBI there was a significant decrease in expression of tyrosine hydroxylase and dopamine transporter in the substantia nigra as well as significant behavioral alterations. In addition, a strong increase in neuroinflammation was evident, as shown by increased levels of cyclooxygenase-2 and inducible nitric oxide synthase as well as IκB-α degradation and nuclear-κB translocation. Moreover, neurotrophic factors such as brain-derived neurotrophic factor, neurotrophin-3, nerve growth factor, and glial cell line-derived neurotrophic factor were decreased 30 days post-TBI. Interestingly, we observed a significant accumulation of α-synuclein in microglia compared to astrocytes. This study suggests that PD-related molecular events can be triggered upon TBI. The biological mechanisms linking brain trauma and neurodegenerative diseases need to be further investigated.

Role of Autophagy in HIV Pathogenesis and Drug Abuse

Autophagy is a highly regulated process in which excessive cytoplasmic materials are captured and degraded during deprivation conditions. The unique nature of autophagy that clears invasive microorganisms has made it an important cellular defense mechanism in a variety of clinical situations. In recent years, it has become increasingly clear that autophagy is extensively involved in the pathology of HIV-1. To ensure survival of the virus, HIV-1 viral proteins modulate and utilize the autophagy pathway so that biosynthesis of the virus is maximized. At the same time, the abuse of illicit drugs such as methamphetamine, cocaine, morphine, and alcohol is thought to be a significant risk factor for the acquirement and progression of HIV-1. During drug-induced toxicity, autophagic activity has been proved to be altered in various cell types. Here, we review the current literature on the interaction between autophagy, HIV-1, and drug abuse and discuss the complex role of autophagy during HIV-1 pathogenesis in co-exposure to illicit drugs.

Cocaine-mediated microglial activation involves the ER stress-autophagy axis

Cocaine abuse leads to neuroinflammation, which, in turn, contributes to the pathogenesis of neurodegeneration associated with advanced HIV-1 infection. Autophagy plays important roles in both innate and adaptive immune responses. However, the possible functional link between cocaine and autophagy has not been explored before. Herein, we demonstrate that cocaine exposure induced autophagy in both BV-2 and primary rat microglial cells as demonstrated by a dose- and time-dependent induction of autophagy-signature proteins such as BECN1/Beclin 1, ATG5, and MAP1LC3B. These findings were validated wherein cocaine treatment of BV-2 cells resulted in increased formation of puncta in cells expressing either endogenous MAP1LC3B or overexpressing GFP-MAP1LC3B. Specificity of cocaine-induced autophagy was confirmed by treating cells with inhibitors of autophagy (3-MA and wortmannin). Intriguingly, cocaine-mediated induction of autophagy involved upstream activation of 2 ER stress pathways (EIF2AK3- and ERN1-dependent), as evidenced by the ability of the ER stress inhibitor salubrinal to ameliorate cocaine-induced autophagy. In vivo validation of these findings demonstrated increased expression of BECN1, ATG5, and MAP1LC3B-II proteins in cocaine-treated mouse brains compared to untreated animals. Increased autophagy contributes to cocaine-mediated activation of microglia since pretreatment of cells with wortmannin resulted in decreased expression and release of inflammatory factors (TNF, IL1B, IL6, and CCL2) in microglial cells. Taken together, our findings suggest that cocaine exposure results in induction of autophagy that is closely linked with neuroinflammation. Targeting autophagic proteins could thus be considered as a therapeutic strategy for the treatment of cocaine-related neuroinflammation diseases.